The invention refers to a metrology device couplable to a load port of a semiconductor product handling and/or processing tool which tool encloses a mini-environmental atmosphere and has a load port table for supporting devices to be coupled to the load port. The metrology device contains a housing preserving an inner atmosphere, a coupling region for connecting an inner atmosphere to a mini-environmental atmosphere, and a measuring device for measuring a property of a semiconductor product.
In the manufacture of semiconductor products, several process steps are performed by process tools which are, for instance, combined to cluster tools including one wafer handling tool. Within the cluster tools the semiconductor products are handled and processed within a mini-environment that is a clean room atmosphere of higher purity than the clean room atmosphere accommodating operating personnel and the cluster tools. Due to the complexity of modern semiconductor product processing often requires several hundred processing steps, intermediate control of processing results and physical, chemical, or other properties of the semiconductor products is necessary. Often the necessity of controlling such a property arises during semiconductor product processing. In any case, measurements have to be performed during or interrupting, respectively, a rather complex process routine.
With a view to the costs of running processing tools, it would be desirable to minimize the interruption time caused by the measurements. However, due to the mini-environmental clean room requirements, the semiconductor products must not contact the outer atmosphere surrounding the processing tools.
In order to preserve the mini-environmental atmosphere, wafers are intermediately stored in so-called front-opening unified pods (FOUPs) docked at a load port. The load port is a device for loading or unloading FOUPs. Usually, load ports are allocated at front-end process modules for wafer handling and loading and unloading process tools.
The FOUP containing a semiconductor product also preserves the mini-environmental atmosphere around it and hence allows for an air-tight transport of the semiconductor product within the outer clean room atmosphere of minor purity. The semiconductor product in the FOUP is transported to a second load port connected to a measuring tool, unloaded, subjected to the measurement, reloaded and transported to the load port connected to the cluster tool in order to continue the semiconductor processing.
Due to this proceeding, semiconductor products to be measured have to be transported twice. In order to save time and efforts for transport, it would be possible to permanently combine the measurement device with the cluster tool. In this case, FOUP transport would not be required. However, this is not realized up to now because of several reasons.
First, measurement devices are supplied by various engineering companies. Each measurement device of any one of the companies would require high efforts for integration into and interaction with highly automated cluster tools. It is not profitable to spend time and costs for extending the cluster each time when any measurement device of one of the various suppliers is integrated.
Second, such integration efforts would arise already in advance before testing the compatibility of a measurement device and a cluster tool. As the compatibility has to be proven before selecting a measurement device of a particular supplier, the integration costs would add up to the costs of the devices chosen or, with respect to those devices not bought from the other suppliers, would be spent to no purpose.
Finally, present FOUPs and load ports are standardized and therefore offer simple connection to stand-alone measuring devices.
For these reasons, wafers to be subjected to a measurement are transported to and from the load port connected to such measurement device.
A FOUP ordinarily employed for exclusively transporting wafers may contain a sensor for measuring a property of a wafer allocated in the FOUP. As the housing of the FOUP preserves the mini-environment and the FOUP is easily coupled by its coupling region to the cluster tool, the measurement can be performed directly at the load port; the need of transport no longer arises.
The load ports themselves, however, must maintain mini-environmental atmospheric conditions when a FOUP is docked thereto. In no case can any leakage between the FOUP and the load port be tolerated. Therefore, a special seal is located between the load port and the FOUP and surrounds a passage for transferring a wafer between the load port and the FOUP.
Effective passage seals as well as wafer handling require exact positioning of the FOUP relative to the load port. To this end, a load port contains a table with three pins supporting the FOUP when it is docked to the seal of the load port. Exact positioning of the FOUP is provided by the suppliers of the load port only to a certain maximum weight of the FOUP. In 300 mm production, the maximum weight amounts to about 12 kg and approximately corresponds to the weight of a FOUP loaded with the maximum number of wafers allowed.
When a metrology device is integrated in a FOUP, the maximum weight must not be exceeded because otherwise exact positioning could not be granted so that a leakage of the seal might occur. As a consequence, only lightweight metrology devices as sensors requiring little hardware and software equipment can be integrated into a FOUP.
It is accordingly an object of the invention to provide a self-supporting adaptable metrology device which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which, regardless of its dimensions or weight, can rapidly be coupled to a semiconductor product handling and/or processing tool with very little effort and which grants for comparable leakage prevention during coupling and decoupling as the lightweight FOUP does. It is a further object of the invention to provide a metrology device which is adaptable to a semiconductor product handling and/or processing tool via a load port having a load port table and thus being constructed for the coupling of wafer containers (which at the most might contain small and light weight measuring tools) exclusively.
With the foregoing and other objects in view there is provided, in accordance with the invention, a metrology device couplable to a load port of a semiconductor product tool enclosing a mini-environmental atmosphere and having a load port table for supporting devices to be coupled to the load port. The metrology device contains a housing preserving an inner atmosphere, a coupling region for connecting the inner atmosphere to the mini-environmental atmosphere and extends from the housing, a measuring device for measuring a property of a semiconductor product, a transport device, and a support supported by and movable over ground by the transport device. The support supports the housing and the measuring device. The support is dimensioned such that the metrology device is self-supporting in a position appropriate for coupling the coupling region to the load port, the metrology device is thereby couplable to the load port without being supported by the load port table.
According to the invention, the object is achieved by a metrology device of the kind now described which is constructed containing a support which is movable on the ground by the transport device and which support is dimensioned such that the metrology device is self-supporting in a position appropriate for coupling the coupling region to the load port. The metrology device thereby being couplable to the load port without being supported by the load port table.
The general idea underlying the invention is, proceeding from the above-mentioned load port FOUP support, to position the metrology device independently and separately from any maximum weight depending support members of the cluster tool. Whereas according to prior art both mechanical positioning and atmospheric connection or isolation, respectively, are achieved by the load port forming part of the cluster tool, according to the invention merely the atmospheric connection is primarily achieved by the cluster tool whereas mechanical positioning and support are achieved by the metrology device itself regardless of positioning members eventually existing at each cluster tool present.
Preferably, the metrology device is self-supporting on the ground located at a vertical position deeper than the vertical position of the load port table of the load port. Thereby the device is couplable to the load port constructed for light-weight wafer compartments which usually are not self-supporting when supported by the load port table.
To this end, preferably the self-supporting metrology device is constructed such that the coupling region is located in a height appropriate for coupling to the tool. The height corresponds to the sum of the height of the load port table above the ground and the height of a coupling region of the tool (to be engaged with the coupling region of the metrology device) above the load port table. Thus preferably the coupling region is supported in a vertical position higher than the vertical position of an upper side of the load port table.
According to a preferred embodiment the support of the metrology device has a recess for accommodating the load port table. Preferably the recess is dimensioned to accommodate the load port table extending horizontally in front of the load port to which the metrology device is coupable to, the recess being allocated at a deeper vertical position than the coupling region. The recess in the support of the metrology device allows for close approximation of the metrology device and the load port, the load port table being unused for coupling of the metrology device being suitably accommodated in the recess.
Preferably an upper portion of the metrology device including the coupling region is supported in a position preventing contact to contact members. More preferably the upper portion of the metrology device including the coupling region is supported in a position preventing contact to cinematic coupling pins of the load port. A load port contains a three pins for holding a wafer compartment of a predefined range of weight in a predefined vertical (and lateral) position relative to the coupling region of the tool. The pins hinder placing large weight compartments or metrology devices on the load port table since the cinematic coupling pins and their support in the load port table may be damaged by a large weight of a device supported. The standardized load port tables contains pin allocated for FOUP support up to the maximum weight allowed. The contact pins are no longer necessary as according to the invention the metrology device is self-supporting. A gap of at least several millimeters is recommendable between the upper side of the load port table and that portion of the metrology device extending above the load port table in order to prevent unintentional damage of the FOUP support pins when coupling the metrology device to the load port. In contrast to the destine of the load port table and of the cinematic coupling pins, the metrology device is self-supporting in a position appropriate for coupling of the coupling region to the load port. Furthermore, the metrology device is self-supporting in a position appropriate for very quick coupling since the metrology device can slidably or rollably be attached to the tool.
According to a preferred embodiment, the support forms part of the housing preserving the inner atmosphere. Accordingly, a complete volume of the metrology device can be coupled to mini-environmental atmosphere. This saves coupling stations as according to this embodiment several semiconductor products can be measured or various measurements can be performed within one single mini-environmental metrology device. Hence, preferably also the support is constructed to accommodate a measuring device.
Preferably, the support contains means for adapting the position of the metrology device to different sizes of tools. Though load ports are standardized, there are different standard dimensions preventing unique coupling of one single housing lacking any size adaptation facilities. Preferably, the height of the coupling region of the metrology device extending above the load port table may be variable. Thereby any particular metrology device can be coupled to cluster tool coupling regions of different standard sizes.
According to a preferred embodiment of the invention, the metrology device is constructed to receive a semiconductor product through an opening of the coupling region in order to perform the measurement inside the housing. As a consequence, the handling tool of the front-end process module of a cluster tool can be utilized for other handling operations during measurement. Furthermore, performing the measurement in the housing of the metrology device allows for the nearest contact of the measuring equipment to the semiconductor surface from all directions. However, alternatively, the metrology device may interact with the cluster tool, for instance by measurement sensors protruding into an opening of the cluster tool, for performing the measurement.
The transport devices of the support preferably form part of the support. Preferably, they are rollers.
According to another preferred embodiment of the invention, the support contains a docking region mechanically dockable to the tool. This construction may be developed to form further advantageous embodiments.
First, the docking region may contain members for fixing a position of the metrology device relative to the tool. These members may be mechanically lockable pins. Preferably, both the coupling region usually located above as well as the docking region of the support located beneath are equipped with locking members so that stability of the metrology device coupled to the cluster tool is increased in case of uneven ground. However, the coupling region primarily serves to atmospherically couple the metrology device and the cluster tool and isolate them from the surrounding clean room atmosphere of minor purity.
Second, the docking region preferably may contain a conduct region coupleable to the tool. The conduct region serves to supply all media and other sources that are required for driving the metrology device. Thereby a plug-and-play performance of the complete metrology device is granted. Preferably, the conduct region supplies data transfer, power, pressured gas or other media from the tool to the metrology device. Furthermore, the conduct region may contain exhaust lines for exhaust transport of gases from the metrology device to the tool.
With view to the function of the coupling region of connecting the inner atmosphere to the mini-environmental atmosphere, the coupling region preferably contains a respective seal. However, the cluster tool may have a seal instead. Preferably, both the cluster tool and the metrology device contain a respective seal interacting with one another in order to more safely prevent any leakage of mini-environmental atmosphere.
Preferably, the coupling region and/or the support contain elements for vibration damping. Furthermore, the metrology device may contain a table for vibration damping, the table preferably is formed of granite or another kind of stone and configured to have a great mass.
According to advanced preferred embodiments of the invention, the metrology device is configured as a cluster device. Preferably, it is a cluster device containing a measuring device for measuring at least two properties of a semiconductor product. Alternatively or in addition, the metrology device is a cluster tool containing a measuring device for measuring properties of at least two semiconductor products.
According to the invention a system contains a load port for a semiconductor product handling and/or processing tool which tool encloses a mini-environmental atmosphere and has a load port table for supporting devices to be coupled to the load port. The system contains the metrology device as disclosed above. The system provides a new coupling technique of devices to be coupled to a tool having a table for supporting them when being coupled. The coupling technique according to the invention is independent of table dimensions and of the weight of the device.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a self-supporting adaptable metrology device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.